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Development of Corrosion Inhibitors for Absorption Heat Pumps--Advanced Mechanical Technology, Inc., 176 Waltham Street, Watertown, MA 02172-4809; 617-926-6700
Dr. Joseph Gerstmann, Principal Investigator
Mr. Andrew D. Vasilakis, Business Official
DOE Grant No. DE-FG02-98ER82519
Amount: $617,764
In order to compete effectively in the marketplace, advanced absorption heating and cooling systems need to utilize low-cost materials of construction, such as carbon steel. Due to the corrosive nature of the ammonia-water working fluid, a chemical inhibitor is required to protect carbon steel, which lacks the corrosion resistance of alloys such as stainless steel. Historically, highly toxic chromate compounds have been used as corrosion inhibitors for steel in ammonia-water absorption systems. A non-toxic, but effective replacement is needed. This project will develop an effective, non-toxic corrosion inhibitor for use in ammonia-absorption systems as an alternative to chromate based formulations. Phase I demonstrated that cerium nitrate, a rare earth metal salt, had a corrosion inhibition efficiency comparable to that of chromate based inhibitors. An innovative, low-cost test rig was developed to provide a range of pressure, temperature, and concentration conditions typically found in ammonia-water absorption systems; in this way, costly tests in actual absorption systems could be avoided. Phase II will pursue the development of a dual corrosion protection strategy: using cerium salts as a corrosion inhibitor and optimizing the surface pretreatment process. A prototype corrosion protection protocol will be specified and tested in commercially available absorption equipment.
Commercial Applications and other Benefits as described by the awardee: A practical corrosion inhibitor should provide long service life and acceptable cost for high-efficiency absorption heating and cooling systems. An environmentally safe alternative would be provided for the toxic heavy-metal inhibitors currently in use.